Anthropogenic N deposition slows decay by favoring bacterial metabolism: Insights from metagenomic analyses

Zachary B. Freedman, Rima A. Upchurch, Donald R. Zak, Lauren C. Cline

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Litter decomposition is an enzymatically-complex process that is mediated by a diverse assemblage of saprophytic microorganisms. It is a globally important biogeochemical process that can be suppressed by anthropogenic N deposition. In a northern hardwood forest ecosystem located in Michigan, USA, 20 years of experimentally increased atmospheric N deposition has reduced forest floor decay and increased soil C storage. Here, we paired extracellular enzyme assays with shotgun metagenomics to assess if anthropogenic N deposition has altered the functional potential of microbial communities inhabiting decaying forest floor. Experimental N deposition significantly reduced the activity of extracellular enzymes mediating plant cell wall decay, which occurred concurrently with changes in the relative abundance of metagenomic functional gene pathways mediating the metabolism of carbohydrates, aromatic compounds, as well as microbial respiration. Moreover, experimental N deposition increased the relative abundance of 50 of the 60 gene pathways, the majority of which were associated with saprotrophic bacteria. Conversely, the relative abundance and composition of fungal genes mediating the metabolism of plant litter was not affected by experimental N deposition. Future rates of atmospheric N deposition have favored saprotrophic soil bacteria, whereas the metabolic potential of saprotrophic fungi appears resilient to this agent of environmental change. Results presented here provide evidence that changes in the functional capacity of saprotrophic soil microorganisms mediate how anthropogenic N deposition increases C storage in soil.

Original languageEnglish (US)
Article number259
JournalFrontiers in Microbiology
Volume7
Issue numberMAR
DOIs
StatePublished - Mar 2 2016

Keywords

  • C storage
  • Climate change
  • Metagenome
  • N deposition
  • Saprotroph

Fingerprint Dive into the research topics of 'Anthropogenic N deposition slows decay by favoring bacterial metabolism: Insights from metagenomic analyses'. Together they form a unique fingerprint.

Cite this